Working on my own definitions for certain types of relationships

Because the trio of friend/coworker/acquaintance just doesn't do things specifically enough in 2024.

Sorted with closest type of relationship first, more or less.

Friend

Mutual status.
Relationship often originally forms over other shared connection (spouse’s friend’s spouse, kids the same age, etc) or situation (job, class) but sticks around without that connection continually. Because of this, it can be hard to determine if someone is a true friend until after the situation behind the situationship ends.
The kind of relationship where you both might wish each other a birthday without being socially pressured to do so.
Close enough to ask a favour of without feeling like you need to keep score.
Able to function as a sounding board to get something out (e.g. complaining about one's spouse) without having to share it somewhere inadvisable.
Will stick around even when you disagree.

Partner

Mutual status.
Person one is in a legally-defined relationship with.

Coworker

Mutual status.
Like a colleague.
On a similar level of employment; not boss/underling.
Working together—on projects, not just in the same room or something—to some extent.

Arms-length friend or Friends Lite

Not necessarily mutual.
You might call yourself a friend of someone, but you're not close enough to ask them to help you move or redo your roof. You still enjoy an opportunity to catch up.
May be a former true friend.

I have other old friend who, we’re like “arms length” friends.

We’ll maybe chat online here and there. But basically never meet up or anything else. It’s fine and I consider those people to be current/active friends.

— A friend of mine

Friend-in-law

Not necessarily mutual.
A person that one would not be friends with if it wasn't for their partnership with an actual friend.

Colleague

Mutual status.
A person at the same company as you whom you at least make eye contact with, Slack-react with, or __ at least once a month.
Not necessarily working together on tasks.
Can be used to describe one's boss/underling in situations where the specificity is not needed or helpful.

Family friend(s)

Usually mutual status.
Used in two ways:
1. Plural: a family which as a fair amount of overlap of friends with your own, so you can do activities with your family and theirs as a group.
2. Singular: a person whom you know and aren't friends with, have a connection to through a member of your immediate family.

Situationship

Mutual status.
This one needs a noun form so it's not just "I'm in a ___ with so-and-so.
When you get along well with someone in specific situations but the relationship doesn’t extend outside of those in a way that a friendship would.
Coworker and colleague are types of situationship.

Acquaintance

Not necessarily mutual.
Someone you've met in either meat- or cyber-space.

Comrade

Not necessarily mutual.
One that you mainly interact with because of shared political opinions.

Parasocial relationship

Not necessarily mutual.
This one needs a noun form so it's not just "I'm in a ___ with so-and-so.
When you feel like you know a person because you listen to them a lot (hat tip to Ed and J(e)D on The Pillar for naming this)